A way of isolating laboratory test animals from each other and from the personnel and, at the same time, of reducing operating costs is to enclose them, either alone or in small homogeneous groups, in containers, usually small cages. Inside the cages the most convenient microclimate for the life of the animals is realized. Great care is taken to provide the container inside with a change of air adequate for maintaining low levels of ammonia and carbon dioxide concentrations, which substances are harmful to the animals good health.
These cages are provided with means connecting the same with a pipe (or equivalent system) conveying air (generally filtered and decontaminated) at the desired pressure: the connecting system will maintain—at least for a short time—the container isolated and protected from the external environment, should the container be disconnected from the pipe and moved for any reason.
The cages are generally placed on racks (either open or closed by doors or the like) attached to a framework, which is the stationary component of the breeding department. This support framework is provided with a system that supplies the single cages with air and, preferably, but not necessarily, with the water to be conveyed to the drinking-troughs, if any.
The known cages are normally closed by a plastic top equipped with latches, inlet and outlet air valves, external water bottle and, inside the cage, a wire bar lid with a nylon gasket fitted on the upper profile of the cage base.
The problems to be faced with the above kind of cages are an increasing need for improving the containment at cage level while keeping the practicality of use, reducing the number of cage components, increasing the number of cages within the rack footprint and standardising of rack structure.
A further problem also to be solved is to improve the manner for positioning and keeping stable and firm the cages to the rack.